The effect of ChAdOx1 nCov-19 vaccine on arterial thrombosis development and platelet aggregation in female rats

ChAdOx1 nCoV-19 adenoviral vector vaccine (ChAd) against coronavirus disease 2019 has been associated with vaccine-induced thrombosis and thrombocytopenia (VITT), especially in young women who have presented with unusual localized thrombosis after receiving the vaccine. The pathogenesis of VITT remains incompletely understood. We tried to provide new insights into mechanisms underlying this phenomenon in the model of arterial thrombosis electrically induced in the carotid artery of female rats. At 28 days post-vaccination, ChAd induced SARS-CoV-2-specific neutralizing antibody responses in all animals. The analysis of the blood vessel/thrombus area showed slight luminal narrowing of the carotid artery with extravasation of blood in vaccinated rats. These small changes were not accompanied by differences in thrombus weight and composition. The vaccinated animals presented a slight increase (by around 14–24%) in platelet aggregation. ChAd did not significantly affect blood coagulation, platelet counts, and their activation markers. Unaffected thrombus formation, the lack of thrombocytopenia and all the measured blood and hemostasis parameters that predominantly stayed unchanged, indicate that the ChAd does not increase the risk of arterial thrombosis development in female rats.     

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

BACKGROUNDToday, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads.AIMTo compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits.METHODSThe study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet''s Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred.RESULTSThe breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001).CONCLUSIONTANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.     

SARS-CoV-2 host diversity: An update of natural infections and experimental evidence

Coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is now a pandemic threat. This virus is supposed to be spread by human to human transmission. Cellular angiotensin-converting enzyme 2 (ACE2) is the receptor of SARS-CoV-2 which is identical or similar in different species of animals such as pigs, ferrets, cats, orangutans, monkeys, and humans. Moreover, a recent study predicted that dogs might be secondary hosts during the evolution of SARS-CoV-2 from bat to human. Therefore, there is a possibility of spreading SARS-CoV-2 through domestic pets. There are now many reports of SARS-CoV-2 positive cases in dogs, cats, tigers, lion, and minks. Experimental data showed ferrets and cats are highly susceptible to SARS-CoV-2 as infected by virus inoculation and can transmit the virus directly or indirectly by droplets or airborne routes. Based on these natural infection reports and experimental data, whether the pets are responsible for SARS-CoV-2 spread to humans; needs to be deeply investigated. Humans showing clinical symptoms of respiratory infections have been undergoing for the COVID-19 diagnostic test but many infected people and few pets confirmed with SARS-CoV-2 remained asymptomatic. In this review, we summarize the natural cases of SARS-CoV-2 in animals with the latest researches conducted in this field. This review will be helpful to think insights of SARS-CoV-2 transmissions, spread, and demand for seroprevalence studies, especially in companion animals.     

重组人骨形成蛋白2-珊瑚复合人工骨修复骨质缺损的实验研究

目的弥补珊瑚无骨诱导活性、成骨能力弱等缺陷。方法将珊瑚与重组人骨形成蛋白２（ｒｅｃｏｍｂｉｎａｎｔｈｕｍａｎｂｏｎｅｍｏｒｐｈｏｇｅｎｅｔｉｃｐｒｏｔｅｉｎ－２，ｒｈＢＭＰ－２）复合，制备出ｒｈＢＭＰ－２－珊瑚复合人工骨。将其植入兔颅骨直径１５ｍｍ的圆形缺损，以单纯珊瑚植入作对照。术后２、６、１２周取材，通过组织学观察和计算机图像分析，评价其骨修复能力。结果ｒｈＢＭＰ－２－珊瑚复合人工骨以传导成骨和诱导成骨双重机制完成骨修复过程，骨修复能力和骨修复效果明显优于单纯的珊瑚。结论此复合人工骨是一种较理想的骨移植替代材料。     

渐进性咬合紊乱导致兔髁突退行性变的研究

目的 探讨渐进性咬合紊乱是否可导致兔髁突软骨退行性变。方法 27只5月龄雄性新西兰大白兔，随机分为渐进性咬合紊乱组(A组)、操作对照组(B组)和空白对照组(C组)。A组动物以正畸用橡皮圈分别将一侧上颌和对侧下颌第一前磨牙向近中牵拉，以形成上下牙不吻合接触的咬合紊乱；B组作结扎钢丝操作对照，不牵拉。分别在6月龄、7月龄、8月龄时取材，各时间点每组取材3只实验动物，对双侧髁突作组织学观察和测量。结果 B、C两组髁突软骨表现无明显差异，A组有明显随时间延长而加重的退行性变，表现为髁突前、中部软骨变薄，肥大层软骨不连续，局部组织纤维化；髁突后部软骨增厚，增殖层未成熟细胞比例增加。结论 渐进性咬合紊乱可导致兔髁突软骨退行性变。     

应用牵张成骨整复腭裂的动物实验研究

目的：应用研制的腭裂整复牵张装置行腭裂牵张成骨整复术，探索腭裂功能性整复治疗的新途径。方法：以家猫14只为实验对象，用12只猫建立人工腭裂的实验动物模型，其中2只为实验对照组，另10只作为实验组，在建立腭裂的同时每只动物均在上颌腭侧安置自行研制的腭裂牵张装置，4周后，于裂侧腭部形成单骨运送盘，术后第6日起，以每次0．4mm的速度，每日2次向恒定的方向行牵张成骨术，直到腭部软硬组织裂隙完全封闭，于原位固定2，4，6，8及12周后各时间分别处死实验动物各2只，按计划项目对标本测量，X线摄片，从大体到超微结构系列检测。结果：利用该腭裂口内牵张装置，成功地进行了腭裂牵张整复术。腭部裂隙软硬组织缺损在获得相同组织修复的基础上，裂隙封闭；骨牵张间隙完全为新生骨组织取代，腭裂整复后对牙颌颅面框架及其相互关系无明显影响。结论：自行研制的口内腭裂牵张装置设计合理，性能良好，牵张成骨腭裂整复术开拓了腭裂整复治疗的新途径，为临床应用提供了理论和实验根据。     

PerioGlas/rhBMP-2用于兔下颌骨侧嵴扩增的初步实验评估

目的 探讨PerioGlas（bioaetive glass，BG）与重组人骨形成蛋白-2（recombinent human bone morphogenetic protein-2，rhBMP-2）在下颌骨侧嵴扩增的可行性。方法在免磨牙区唇侧骨皮质表面，球钻预备4～6个5mm的骨缺损，一侧骨皮质表面和骨缺损内放置BG／rhGBMP-2，另一侧作为空白对照。术后正常饮食，2、4、8周后大体观察、组织学检查和组织学测量。结果观测时间内所有植入体固住良好，没有炎性反应。下颌骨表面明显加厚。材料表面骨组织覆盖；组织学观察皮质骨表面和骨缺损内新骨形成，2周纤维组织分割BG颗粒，4周大量新生骨呈编织骨样结构，新骨与BG颗粒直接结合。8周部分BG颗粒已降解被新骨取代，并与植骨床骨皮质表面直接结合，极少量残留颗粒被新骨包围。rhBMP-2／BG的表面成骨作用比单一BG、rhBMP-2好，具有明显的骨诱导性和骨引导性。新骨形成百分比明显高于BG（P〈0．05）。临床操作性能佳，易于放置，有止血作用。结论rhBMP-2／13G可以用于下颌骨侧嵴扩增。     

酪氨酸激酶抑制剂GW2974对口腔鳞状细胞癌生长抑制作用的实验研究

目的评价表皮生长因子受体酪氨酸激酶抑制剂GW2974对由二甲基苯并蒽（dimethyl-benzanthracene，DMBA）诱导的金黄地鼠颊囊癌发生模型的抑制作用。方法100只金黄地鼠，10只为阴性对照，其余90只于左侧颊囊涂0．5％DMBA，每周3次。6周后随机分为阳性对照组、GW2974低浓度组、GW2974高浓度组。阳性对照组不做处理，其余两组于左侧颊囊涂不同浓度的（4mmol／L，8mmol／L）GW2974。24周末处死所有动物，取左侧颊囊黏膜，计算肿瘤发生率、平均肿瘤数目、肿瘤体积和肿瘤负荷，光镜下观察各组单纯增生、异常增生和鳞癌数目并计算鳞癌的发生率。结果通过局部应用4mmol／L和8mmol／L的GW2974，肿瘤发生率从80．0％分别下降到43．3％（13／30，P〈0．01）和36．7％（11／30，P〈0．01），平均肿瘤数目从1．00±0．87分别下降到0．57±0．82（P〈0．05）和0．43±0．63（P〈0．05），平均肿瘤体积和平均肿瘤负荷均逐渐降低，口腔鳞状细胞癌发生率分别从70．0％下降到40．0％（12／30，P〈0．05）和33．3％（10／30，P〈0．01），口腔鳞状细胞癌数目分别从1．83±1．91下降到0．67±0．99（P〈0．05）和0．43±0．68（P〈0．01）。结论局部应用GW2974可明显抑制金黄地鼠颊囊癌的发生，提示GW2974对口腔癌可能具有较强的癌症化学预防和治疗作用，口腔黏膜局部用药可能是预防和治疗口腔癌的一个有效途径。     

小型猪双侧腮腺萎缩后唾液流率及口腔细菌变化的观察

目的 观察小型猪腮腺萎缩后混合唾液流率的变化以及对口腔主要致病菌的影响.方法 10只小型猪分成两组,每组5只,其中一组双侧腮腺注入甲紫致腺体萎缩,另5只作为健康对照组.分别在萎缩后第12、24个月收集混合唾液并观察唾液流率的变化;同时检测小型猪龈下菌斑和混合唾液中口腔主要致病菌数量并与健康对照组比较.结果 腮腺萎缩后第12个月混合唾液流率自(1.36±0.74)ml/min下降到(1.32±0.65)ml/min,第24个月唾液流率自(0.72±0.34)ml/min上升到(0.86±0.57)ml/min;龈下菌斑中的核梭杆菌、后牙龈下菌斑中厌氧菌总数、产黑菌数量均明显高于健康对照组;第12个月前牙和第24个月后牙的龈下菌斑中变形链球菌有短暂升高,而需氧菌总数、乳酸菌和放线菌数量无明显变化.唾液中除变形链球菌和产黑菌在腮腺萎缩早期有轻度上升外,其余细菌数量均无明显变化.结论 双侧腮腺萎缩后明显降低口腔中唾液总量,导致牙菌斑中的致龋菌和牙周致病菌数量上升.     

纳洛酮对神经元GluR2表达的影响及缺氧损伤保护作用

目的：研究纳洛酮对缺氧损伤神经元膜表面AMPA（amino-3-hyoroxy-5-methylisoxazole-4-propionicacid，α-氨基-3-羟基-5甲基-4-异噁唑丙酸）受体在谷氨酸受体第二亚单位（GluR2，glutamic acid receptor 2）表达的影响及其对神经细胞凋亡的保护作用。方法：取体外培养12d的大鼠海马神经元，建立缺氧再灌注损伤模型，分别采用流式细胞和双重免疫荧光技术定量观察神经元凋亡数量、胞膜表面GluR2含量变化及纳洛酮的调节作用。结果：纳洛酮可上调缺氧损伤后神经元膜GluR2的含量（P〈0.05），减少缺氧诱导的神经元凋亡的数量（P〈0.01）。结论：纳洛酮通过上调神经元膜表面GluR2含量，减少神经元凋亡，减轻继发性脑损害。